Robust uranium-capturing membranes enabled by synergistic sulfonation and thiol-ene click crosslinking

Conventional amidoxime-based adsorbents for uranium extraction from nuclear wastewater are constrained by the trade-off between adsorption capacity and mechanical stability. A robust self-supporting adsorptive membrane is engineered through synergistic sulfonation and ultraviolet (UV)-assisted thiol-ene click crosslinking of sulfonated poly(arylene ether nitrile). Incorporation of photo-crosslinkable allyl groups constructs a rigid-flexible three-dimensional network that suppresses excessive swelling and structural collapse while preserving functional site accessibility. Within this architecture, electronegative sulfonic acid/sulfonate groups facilitate U(VI) diffusion and local enrichment through hydrophilicity enhancement and electrostatic interactions, thereby promoting subsequent amidoxime-dominated uranyl chelation. The membrane exhibits a high uranium adsorption capacity of 488 mg g⁻¹, reaches equilibrium within 24 h, and retains approximately 87% capacity after seven cycles. A tensile strength of ∼2.3 MPa surpasses most reported analogues, demonstrating improved structural robustness. Density functional theory DFT calculations further reveal the stronger intrinsic affinity of amidoxime sites toward U(VI) compared with sulfonate groups, supporting an amidoxime-dominated chelation mechanism assisted by sulfonic-mediated enrichment. This work provides a promising structural design strategy for robust uranium adsorptive membranes under complex aqueous environments relevant to uranium-containing wastewater treatment.